G 蛋白激活
中文名称
通路描述
G 蛋白激活是指受体激活的异三聚体 G 蛋白，由 Galpha 和紧密关联的 Gbeta-gamma 亚基组成。当配体结合到 G 蛋白偶联受体时，会稳定一种具有高亲和力与 G 蛋白结合 GDP 的构象。随后，GDP 被 GTP 交换到 Galpha 亚基上。这种交换触发了 Galpha 亚基与 Gbeta-gamma 二聚体及受体的解离。Galpha-GTP 和 Gbeta-gamma 随后可调节不同的信号级联和效应蛋白，而受体也能激活另一个 G 蛋白，从而形成放大级联。Galpha 亚基最终会通过其固有的酶活性水解附着的 GTP 为 GDP，使其能够重新与 Gbeta-gamma 结合并启动新循环。
英文描述
Regulation of ornithine decarboxylase (ODC) Polyamines increase the production of antizyme (AZ). The carboxy-terminal half of antizyme interacts with ODC, generating an inactive AZ:ODC heterodimer complex. A carboxy-terminal domain of ODC is exposed only within the heterodimer, and is the target for subsequent degradation. A domain within the amino-terminal portion of antizyme provides a function needed for efficient degradation of ODC by the proteasome.
The proteasome cycle starts with the processing of AZ:ODC, sequestering ODC and then degrading it to peptides but releasing AZ. AZ participates in additional rounds of binding and degradation. Antizyme-mediated inhibition and destruction of ODC reduces synthesis of polyamines. Additionally, antizyme also inhibits polyamine transport into the cell. Antizyme production is reduced, completing the regulatory circuit (Coffino 2001; Kahana et al. 2005; Murakami et al. 2000; Pegg 2006).
The proteasome cycle starts with the processing of AZ:ODC, sequestering ODC and then degrading it to peptides but releasing AZ. AZ participates in additional rounds of binding and degradation. Antizyme-mediated inhibition and destruction of ODC reduces synthesis of polyamines. Additionally, antizyme also inhibits polyamine transport into the cell. Antizyme production is reduced, completing the regulatory circuit (Coffino 2001; Kahana et al. 2005; Murakami et al. 2000; Pegg 2006).
所含基因
38 个基因